Field of the Invention
Embodiments of the disclosure generally relate to obtaining and analyzing core samples from geological formations. More specifically, the present disclosure relates to methods and systems for preserving original pore fluids and rock properties in collected core samples and enabling effective imaging of such samples.
Description of the Related Art
Wells may be drilled into rocks to access fluids stored in geological formations having hydrocarbons. Such a geological formation may be referred to as a “reservoir.” A variety of techniques exist for determining the presence and amount of hydrocarbons in such reservoirs. In some instances, a sample of rock and fluids (referred to as a “core sample”) may be collected downhole in the wellbore of the well and retrieved to the surface for further analysis. The core sample may be analyzed to quantify the amount and value of hydrocarbons (e.g., oil and gas) in the reservoir. The analysis of a core sample may also determine the rate at which the identified oil and gas may be produced and aid in identifying techniques for extracting the oil and gas and maximizing recovery from the reservoir.
However, obtaining an unaltered core sample from a reservoir may be challenging and may impact accurate analysis of the sample and subsequent quantification of hydrocarbons in the reservoir. Existing techniques for obtaining a core sample from a reservoir may stress the rocks and fluids in the sample and cause changes in the rock properties, fluid properties, or both. Additionally, core samples obtained by existing techniques may have fluid compositions that differ from the native fluid compositions, especially for core samples of rock having a relatively low permeability. Moreover, for hydrocarbons such as tight shale gas and tight shale oil, it may be difficult to obtain the original gas-in-place, and a core sample from such reservoirs may contain volatile fluids and highly compressible gases that expand as the sample is depressurized during retrieval to the surface, further impacting analysis of the core sample.